Our method of MU discussions as a whole are flawed and are mostly theorycraft.
We go about it to be as accurate as possible, but in the end it's all subjective opinion with only videos and frame data to back it up. Most FGCs only stick with frame data and hit confirm reward, then go from there. We're not like that all. We talk about neutral, advantaged, and disadvantaged states and thanks to the complexity of it all, we end up being very inaccurate.
Thanks to the lack of criteria for discussing MUs, a lot of our ratings, even in Melee, are extremely inaccurate and doesn't develop in the way reality works. It also does not account for intensities of a character's advantage/disadvantage and margin of error.
While I disagree with @
|ven|
's list, I'm not going to be one to say he's dead wrong, because I do not have the objective proof to say so. In the end, Smash 4 is the most balanced game in the series thus far, and therefore the gaps of power are noticeably less wide than previous entries. Pretty much every MU can be beaten by outplaying your opponent and you don't have to be considerably better than them.